According to well known stencil printing devices, printing ink is supplied to the interior of a printing drum, and printing paper is pressed, by a press roller, onto a stencil master plate wrapped around the outer circumferential surface of the printing drum to achieve a desired stencil printing. Some of such stencil printing devices are provided with a printing drum which is detachable from the stencil printing device main body so that stencil printing of different colors can be achieved by changing the printing drum as required. Such a stencil printing device is disclosed in Japanese patent publication (kokoku) No. 62-28758.
According to such a stencil printing device, because an ink supply system, including an ink supply pump, an ink level sensor and so on, is provided inside the printing drum, and is controlled by a control unit consisting of a microcomputer or the like provided in the stencil printing device main body, it is necessary to exchange data between the printing drum and the stencil printing device main body.
Conventionally, two halves of a multi-pin connector were provided in the printing drum and the stencil printing device main body, respectively, so that the two halves may be connected to each other by the mounting of the printing drum onto the stencil printing device main body, and the data transmission between the printing drum and the stencil printing device main body may be achieved electrically via the connector and the wiring associated with the connector.
However, according to such a conventional mode of data transmission, as the kinds of data to be transmitted between the printing drum and the stencil printing device main body increases primarily due to the diversification of the kinds of the printing drums, the numbers of pins and wires associated with the connector have to be increased accordingly, and this limits the adaptability of the stencil printing device to the increase in the kinds of data to be transmitted.